Instructions
Measure the keeled tail, which will be broad and wavy in a male and flattened in a female. The keel refers to the shape of the tail, which is used in swimming when the newt is in its mature breeding stage. It is difficult to identify this characteristic if you are looking at a single newt, and even more difficult if the newt is far from maturing out of the eft stage.
Check the cloacal area, which will be swollen in a male and moderate in a female. This will not be a noticeable difference outside of the breeding season. During breeding season, this area will be swollen. Also present at this time are the nuptial pads on the bottom of the legs and feet to bear the weight of the newt during breeding. This characteristic is only identifiable when the efts are close to sexual maturity.
Compare the hind legs to the front legs. The back legs will be enlarged in a male whereas they will be similarly sized to the front legs in a female. This difference may not be noticeable in younger newts as the gender specifics become more pronounced the closer the salamander comes to its aquatic breeding stage.
Search to identify black horny structures on the toes and inner thighs. They will be present in a male and absent on a female's appendages. You may need to get quite close to the newt to identify these. These structures only develop at the end of the eft stage.
How to Tell if a Red Eft Newt Is Male or Female
The Red Eft Newt, or the Notophthalmus viridescens, is commonly known as the Eastern Newt. There are four subspecies that range far in all directions on the eastern portion of the North American continent. The "eft" stage of the newt's growth is after it is two to five months old. It transforms into a mature breeding salamander after two to three years on land, after which it will enter the water to breed and remain there for the rest of its life. Since the newt is still maturing sexually in the eft stage, it is nearly impossible to determine which gender it is.